Normally, polyoxyalkylene polyol is manufactured on the industrial scale by addition polymerization of alkylene oxide to an active hydrogen compound in the presence of potassium hydroxide (abbreviated as KOH) catalyst. Alkylene oxide is continuously introduced into a reactor which is stocked with KOH catalyst and an active hydrogen compound which is the polymerization initiator. Under conditions of reaction temperature 105.about.150.degree. C., maximum reaction pressure 490.about.588 kPa (5.about.6 kgf/cm.sup.2), the reaction is continued until the desired molecular weight is achieved. A crude polyoxyalkylene polyol is obtained. Next, the polyoxyalkylene polyol manufacturing is completed through postprocessing refining steps such as: neutralizing the potassium in the crude polyoxyalkylene polyol with an acid such as inorganic acid, or the like, filtering the potassium which is extracted through dehydration, drying, or the like.
In the prior art, many studies have been done to enhance the production of polyoxyalkylene polyol. For example, known methods for increasing the reaction speed of the monomer alkylene oxide include: increasing the alkylene oxide concentration at the time of the reaction, increasing the amount of catalyst, increasing the reaction temperature, or the like.
However, when using KOH catalyst for addition polymerization of propylene oxide which is the most widely used alkylene oxide, it is known that, with the above method, when the molecular weight of polyoxyalkylene polyol is increased, there is a by product of a monool which has an unsaturated group at the ends of the molecule.
Normally, the monool content corresponds to the total unsaturation degree (represented by C.dbd.C) of the polyoxyalkylene polyol. Because this monool is low molecular weight compared to the polyoxyalkylene polyol generated in the main reaction, it greatly widens the molecular weight distribution of the polyoxyalkylene polyol and lowers the average functional group number. Therefore, whether it is foam or elastomer, the polyurethane resin, which uses a polyoxyalkylene polyol with a high monool content, experience unfavorable results such as increased hysterisis, reduced hardness, reduced extension, reduced curing, increased permanent compression set, or the like.
Many studies have been done in order to suppress the generation of monool by product and to improve production of polyoxyalkylene polyol. For example, in U.S. Pat. No. 3,829,505 and in U.S. Pat. No. 4,472,560, there is proposed a method, wherein: a double metal cyanide complex (abbreviated as DMC) catalyst is used as a catalyst for the propylene oxide addition polymerization. DMC is described as performing very well as a polymerization catalyst for polypropylene oxide.
However, when using DMC as a catalyst for the addition polymerization of ethylene oxide as the alkylene oxide, DMC is first deactivated by reactions with an oxidant such as gas which contained oxygen, peroxides, sulfuric acid, or the like. Catalyst residue is separated from the polyol. Furthermore, there is a need to addition polymerize ethylene oxide using a catalyst of an alkali metal hydroxide such as KOH or an alkali metal alkoxide or the like (U.S. Pat. No. 5,235,114).
Furthermore in U.S. Pat. No. 5,093,380 (Column 2, lines 58.about.68), there is disclosed a manufacture method for a flexible polyurethane foam which uses a polyoxyalkylene polyol having a low C.dbd.C. This kind of polyoxyalkylene polyol having a low C.dbd.C is obtained in the presence of a catalyst other than an alkali catalyst. For example, the catalyst can be diethyl zinc, iron chloride, porphyrin metal, DMC or the like. DMC catalyst is described as a particularly favorable catalyst.
Furthermore, in Japanese Laid-Open Publication No. 4-59825, when manufacturing a polyether using DMC, if the initiator is low molecular weight, problems, such as the reaction of the monoepoxide not occurring or else the reaction speed being extremely slow, are described. In order to solve these problems, it is necessary to use an initiator of a polyoxypropylene glycol which has already addition polymerized a propylene oxide. However, with this method, there is a limitation on the usable polymerization initiator and the manufacturing process becomes complicated.
When polyoxyalkylene polyol is made to be a high molecular weight, there is a tendency for the viscosity of polyoxyalkylene polyol to increase. When DMC is used, this trend is particularly noticeable.
In U.S. Pat. No. 5,300,535, because the viscosity of the high molecular weight polyoxyalkylene polyol which uses DMC as a catalyst is high, the use of acrylate, vinyl ether compounds as viscosity lowering agents is demonstrated (Column 2, line 5.about.column 4, line 12). As a result of research by the present inventors, when the viscosity of polyol is high, troubles of molding stability and mixing properties occur in the mechanical molding of flexible polyurethane foams. There are also problems of inferior processability and reduced mixing properties with auxiliary agents.
In Japanese Laid Open Publication No. 7-278289, there is disclosed a polyoxyalkylene polyol, wherein: it has a hydroxide value (abbreviated as OHV) of 10.about.35 mg KOH/g, a maximum monool content of 15 mol %, and a minimum selectivity for Head-to-Tail (abbreviated as T-H) bond of 96%. Furthermore, in this publication, the catalyst for manufacture of polyol is an alkali metal hydroxide which has a purity of 90% by weight or greater and is a composition which contained at least one compound selected from: cesium hydroxide or rubidium hydroxide. The above polyoxyalkylene polyol has a low viscosity even when the monool content is reduced. The resulting flexible polyurethane foam has good mechanical properties. It is a polyoxyalkylene polyol with excellent properties. However, in order to manufacture a polyoxyalkylene polyol with OHV of 15 mgKOH/g and a monool content of 15 mol % or less while using cesium hydroxide as the catalyst, a long reaction time is required. When considering the productivity of the polyol, it is not necessarily a satisfactory catalyst.
For a polymer-dispersed polyol with polyoxyalkylene polyol as the dispersion medium and a polyurethane which uses the polymer-dispersed polyol, their properties are greatly influenced by the structure and composition of the polyoxyalkylene polyol which is the dispersion medium.
In Japanese Laid-Open Patent Publication No.3-14812, a manufacturing method for a polymer dispersed polyol which has polyoxyalkylene polyol as the dispersing medium is demonstrated. The polyoxyalkylene polyol is obtained using diethyl zinc, iron chloride, metal porphyrin, DMC as a catalyst. Furthermore, by reducing the C.dbd.C in the polyoxyalkylene polyol, it is stated that the properties of the flexible polyurethane foam which uses the polymer dispersed polyol which has this polyol as a dispersing medium are improved. However, research was conducted by the present inventors on this polymer dispersed polyol which has a polyoxyalkylene polyol as the dispersing medium where the polyoxyalkylene polyol is catalyzed by DMC. The polymer dispersed polyol was found to have a high viscosity, and the flexible polyurethane foam which uses this polymer dispersed polyol was inferior in humid aged compression set.
In Japanese Laid Open Patent Publication Number 7-330843, there is disclosed a polymer dispersed polyol, wherein a polyoxyalkylene polyol is the dispersing medium; the polyoxyalkylene polyol has OHV of 10.about.35 mg KOH/g, a monool maximum content of 15 mol %, and a minimum selectivity for H-T bond of 96% by propylene oxide addition polymerization. This polyol is manufactured with an alkali metal catalyst which contains at least one compound of cesium hydroxide or rubidium hydroxide of at least 90 weight % purity. The polymer dispersed polyol which has the above polyoxyalkylene polyol as a dispersed medium has a stable dispersion even when polymer concentration is made high. However, as described above, when using the above catalyst, in order to produce polyoxyalkylene polyol which has a reduced monool content, the manufacturing time becomes long. When taking into account the productivity of polyol and polymer dispersed polyol, it is not a completely satisfactory method.
With regard to the isocyanate terminated prepolymer which is obtained by reacting polyoxyalkylene polyol and polyisocyanate compound, the structure and composition of the polyoxyalkylene polyol has a great influence on the properties of the prepolymer and the polyurethane resin which uses the prepolymer.
In U.S. Pat. No. 5,096,993 and in U.S. Pat. No. 5,116,931, the following inventions are demonstrated: an isocyanate terminated prepolymer which is produced by reacting a polyisocyanate compound and a polyol which has a low C.dbd.C by using a DMC catalyst; a thermoplastic polyurethane elastomer (U.S. Pat. No. 5,096,993) and a thermosetting polyurethane elastomer (U.S. Pat. No. 5,116,931) which uses the isocyanate terminated prepolymer. In U.S. Pat. No. 5,096,993, in order to obtain a low hardness polyurethane elastomer, a high molecular weight polyol (number average molecular weight 2,000-20,000) with a C.dbd.C of 0.04 meq./g or less is described to be advantageous. Furthermore, when the number average molecular weight is less than 4,000, it is stated that the amount of oxyethylene group is preferably less than 35 weight %. In the embodiments (polyol A, C, D), polyols are described as having oxyethylene group content of 7.about.23%.
However, for the polyol with an oxyethylene group, after addition polymerizing propylene oxide using DMC catalyst, an alkali metal catalyst such as potassium hydroxide must be further used in conjunction to addition polymerize ethylene oxide. As a result, the manufacturing step becomes complex. Furthermore, as described previously, when the polyoxyalkylene polyol is made into a high molecular weight, there is a tendency for the viscosity of polyoxyalkylene polyol to increase. In particular, when DMC is the catalyst, this trend is even more obvious. As a result, because the viscosity of the isocyanate terminated prepolymer which has been reacted with the polyisocyanate compound also increases, the processability is reduced.
In Japanese Laid Open Publication Number 6-16764, there is a description of a polyurethane curing composition, wherein: an isocyanate terminated prepolymer is a curing component; the isocyanate terminated prepolymer is obtained by reacting a polymer dispersed polyol and an organic polyisocyanate; the polymer dispersed polyol is a polyoxyalkylene polyol with a hydroxyl group number 1.5 or greater, OHV of 5.about.80 mg KOH/g, C.dbd.C of 0.07 meq./g or lower and contains a polymer consisted of monomers which contained a polymerizing unsaturated group. In the embodiment, the manufacturing method of the polyoxyalkylene polyol is not stated, but in column 2 line 33.about.39, it is stated that the above polyol is obtained by using DMC as a catalyst. However, according to the opinion of the present inventors, a polymer dispersed polyol, where DMC catalyzed polyol is used as the dispersed medium, has a high viscosity. The isocyanate terminated prepolymer which uses these will also have the problem of high viscosity. Furthermore, in order to have ethylene oxide copolymerized to the end of the polyol, an alkali metal catalyst such as KOH is needed, and the manufacturing process becomes complicated.
When an isocyanate terminated prepolymer is manufactured by reacting a polyol and a polyisocyanate compound aromatic polyisocyanate compounds such as 2,4-toluenediisocyanate, 2,6-toluenediisocyanate or the like are widely used. However, normally, some free, unreacted polyisocyanate compound remain in the prepolymer in which an aromatic polyisocyanate compound is used. In this case, not only does toxicity become a problem, but when manufacturing a polyurethane elastomer, the regulation of the reaction with chain extenders becomes difficult. There are also problems of hysterisis in the resulting polyurethane elastomer becoming large.
In Japanese Examined Patent Publication No. 6-13593, in order to solve these problems, there is disclosed a prepolymer composition, wherein: a mixture of 2,4- and 2,6-toluenediisocyanate which contained 1 weight % or greater of the 2,6-isomer and a polyol is reacted at NCO group and OH group equivalent ratio of 2.5.about.5.0 or lower; afterwards, free toluenediisocyanate is removed by vacuum distillation until a content of 1 weight % or less is achieved.
The prepolymer composition is described as providing a polyurethane elastomer with a long pot life and with an improved hysterisis. In this publication, it is stated that a polyol with average molecular weight of 200.about.6,000 is used. However, in this publication, there is no reference to the advantages of using a polyol with a low monool content.
In order to improve the mechanical properties of the polyurethane elastomer, there have been many studies from the prior art regarding isocyanate terminated prepolymers which have a low monool content and which use a high molecular weight polyoxyalkylene polyol. As described above, in U.S. Pat. No. 5,096,993 and in U.S. Pat. No. 5,116,931, there is described an isocyanate terminated prepolymer which uses a polyol which is catalyzed by DMC and which has a low monool content. However, the relationship between the prepolymer in which a polyol with a low content of monool is used and in which the content of free isocyanate is reduced and the mechanical properties of the polyurethane obtained from this prepolymer is not described.
Next, a polyoxyalkylene polyamine of the prior art is described. Because polyoxyalkylene polyamine is highly reactive with polyisocyanate compounds, it is mainly used as the material for polyurethane urea resin which is molded by spray method or reaction injection molding (abbreviated as RIM). Normally, spray method and RIM method are processes with extremely fast cycling times. Because molded products can be obtained in 2.about.4 seconds, a large amount of reaction heat is generated in a short amount of time. As a result, the thermal properties of the resin in the molding process is important.
In Japanese Laid Open Patent Publication No. 6-16763, there is described a high molecular weight polyol which is catalyzed by DMC, and there is also described a polyamine which is obtained by amine capping of this polyol. Furthermore, because the polyol has a low content of ethylenically unsaturated groups (corresponding to C.dbd.C), the elastomer which is prepared using these is described as having excellent thermal properties characterized by low amount of heat sag and high temperature at heat deformation (column 13, line 19.about.column 14, line 20).
By using DMC as the polymerization catalyst of alkylene oxide, in particular propylene oxide, a high molecular weight polyol with a low C.dbd.C can be obtained. However, as described above, polyoxyalkylene polyol which is obtained with this method has the disadvantage of having a high viscosity.
By the experiments of the present inventors, polyoxyalkylene polyamine in which the precursor is a polyol which is catalyzed by DMC has a high viscosity. When resin is molded by collision mixing such as by spray method or RIM method or the like, the mixing property of the resin is decreased. As a result, the conditions of the surface of the molded product deteriorates. Furthermore, mechanical properties such as elongation hardness, extension strength is reduced.
The first objective of the present invention is to provide a polyoxyalkylene polyol and manufacturing method for the same, wherein: C.dbd.C is low even when an alkylene oxide is addition polymerized to an active hydrogen compound and made into a high molecular weight; H-T bond selectivity is high; and the molecular weight distribution of the polyol of the main reaction component is sharp.
The second objective of the present invention is to provide a polymer dispersed polyol which is derived from the above polyoxyalkylene polyol and which has low viscosity and excellent dispersal stability.
The third objective of the present invention is to provide an isocyanate terminated prepolymer which is derived from the polyoxyalkylene polyol described above and to provide an isocyanate terminated prepolymer which has a low content of free isocyanate compound.
The fourth objective of the present invention is to provide an isocyanate terminated prepolymer which is derived from the above polymer dispersed polyol and which has excellent storage stability.
The fifth objective of the present invention is to provide a polyurethane resin which is derived from the above isocyanate terminated prepolymer and which has excellent mechanical properties, water resistance, and low tack.
The sixth objective of the present invention is to provide a polyoxyalkylene polyamine which has a low viscosity and which is derived from the above polyoxyalkylene polyol.
The seventh objective of the present invention is to provide a polyurethane urea resin which is derived from the above polyoxyalkylene polyamine and which has good surface conditions and excellent mechanical properties.